The present invention relates to an intake manifold formed by bonding a plurality of parts made of synthetic resin to one another, and including a surge tank disposed sideways of an engine body, and a plurality of intake pipes disposed in parallel to one another and each having a rising pipe portion which is connected to a lower portion of the surge tank on a side opposite from the engine body, and extends upwards, a space being defined between the surge tank and each of the rising pipe portions, as viewed sideways in a direction parallel to a direction of arrangement of the intake pipes.
Such an intake manifold is already known, for example, from Japanese Patent Application Laid-open No.10-299591 and the like. In such intake manifold, the surge tank is formed to have a rectangular cross section longer in a direction of arrangement of a plurality of intake pipes, and a space is defined between the surge tank and a rising pipe of each of the intake pipes connected to a lower portion of the surge tank to extend in the direction of arrangement of the intake pipes with its opposite ends opened.
In the intake manifold having the above-described structure, the space between the surge tank and the rising pipe portion of each intake pipe is not utilized effectively, and to increase the volume of the surge tank, while avoiding an increase in size of the intake manifold, it is necessary to effectively utilize the space.
The present invention has been accomplished in view of the above circumstances, and it is an object of the present invention to provide an intake manifold designed so that the volume of a surge tank can be increased, while avoiding an increase in size of the intake manifold.
To achieve the above object, according to a first aspect and feature of the present invention, there is provided an intake manifold formed by bonding a plurality of bonded parts made of synthetic resin to one another, and including a surge tank disposed sideways of an engine body, and a plurality of intake pipes disposed in parallel to one another and each having a rising pipe portion which is connected to a lower portion of the surge tank on a side opposite from the engine body, and extends upwards, a space being defined between the surge tank and each of the rising pipe portions, as viewed sideways in a direction parallel to a direction of arrangement of the intake pipes, characterized in that the surge tank includes a main tank portion extending in the direction of arrangement of the intake pipes and opposed to the rising pipe portions of the intake pipes, and a sideways-bulged portion which is bulged to a side opposite from the engine body from an intermediate portion of the main tank portion as viewed in the arrangement direction to form a cross-sectional T-shape by cooperation with the main tank portion, the sideways-bulged portion being interposed between the rising pipe portions of a pair of the intake pipes disposed at the intermediate portion as viewed in the arrangement direction, and inner ends of a pair of spaces defined respectively between the rising pipe portions of the intake pipes and the main tank portion on opposite sides of the sideways-bulged portion are closed by opposite sidewalls of the sideways-bulged portion.
With such arrangement of the first feature, the cross-sectional shape of the surge tank is a T-shape in such a manner the space defined between the surge tank and the rising pipe portion of each of the intake pipes as viewed sideways in the direction parallel to the direction of arrangement of the intake pipes is bisected. Thus, notwithstanding that the spaces similar to those in the prior art as viewed sideways exist between the surge tank and the rising pipe portions, a portion sandwiched between the spaces can be utilized effectively as a portion of the surge tank, whereby the volume of the surge tank can be increased, while avoiding an increase in size of the entire intake manifold. Moreover, the opposite sidewalls of the sideways-bulged portion forming a portion of the surge tank are disposed at locations displaced inwards from opposite ends of the intake manifold in the direction of arrangement of the intake pipes and hence, a radiated sound from each of the opposite sidewalls of the sideways-bulged portion can be prevented as much as possible from being leaked to the outside.
According to a second aspect and feature of the present invention, in addition to the first feature, the sideways-bulged portion, the rising pipe portions of the intake pipes and the main tank portion are connected together by connecting walls disposed in the spaces respectively. With such arrangement, the rigidity of the surge tank and the intake pipes can be increased, and the radiated sound from the intake manifold can be reduced. Moreover, since the connecting walls are disposed in the spaces, the size of the intake manifold cannot be increased due to the provision of the connecting walls.
According to a third aspect and feature of the present invention, in addition to the second feature, a plurality of the intake pipes are disposed on each of the opposite sides of the sideways-bulged portion, the rising pipe portions of such plurality of intake pipes being connected to each other by the connecting walls. With such arrangement, the rigidity of the plurality of intake pipes is increased and hence, the radiated sound from each of the intake pipes can be reduced.
According to a fourth aspect and feature of the present invention, in addition to the second or third feature, the connecting walls are disposed on a plane intersecting a junction between the parts bonded to each other. With such arrangement, the bond rigidity of the junction at portions corresponding to the connecting walls can be increased.
According to a fifth aspect and feature of the present invention, in addition to any of the second, third and fourth features, a pair of connecting walls are disposed in the space at locations such that the volume of a space portion between a ceiling wall of the space and one of the connecting walls, the volume of a space portion between both of the connecting walls and the volume of a space portion between a bottom wall of the space and the other connecting wall are different from one another. With such arrangement, it is possible to provide an excellent effect of attenuating the radiated sound from the intake manifold.
According to a sixth aspect and feature of the present invention, in addition to the first feature, a lattice-shaped rib is projectingly provided on an outer surface of an end wall of the sideways-bulged portion to connect the rising pipe portions on opposite sides of the sideways-bulged portion to each other, the rib being connected to junctions between the plurality of bonded parts forming at least a portion of the surge tank. With such arrangement, the connection rigidity of the surge tank and both of the intake pipes can be increased remarkably by the lattice-shaped rib. Thus, it is possible to increase the entire rigidity of the intake manifold to reduce the radiated sound. In addition, the rigidity of at least a portion of each of the junctions included in the intake manifold can be further increased by the connection of the rib to the junctions between the plurality of bonded parts forming at least a portion of the surge tank.
According to a seventh aspect and feature of the present invention, in addition to the first feature, the surge tank further includes a pair of downward-bulged portions bulged downwards from opposite ends of the main tank portion and connected to lower ends of the rising pipe portions, and a lattice-shaped rib is projectingly provided on an outer surface of a bottom wall of the central portion of the surge tank sandwiched between the downward-bulged portions to connect the downward-bulged portions to each other, the lattice-shaped rib being connected to a junction between the plurality of bonded parts forming at least a portion of the surge tank. With such arrangement, the lattice-shaped rib is projectingly provided on the outer surface of the bottom wall of the central portion of the surge tank by effectively utilizing an unoccupied space created between the pair of downward-bulged portions. Thus, it is possible to increase the rigidity of the surge tank remarkably, while avoiding an increase in size of the intake manifold, thereby increasing the entire rigidity of the intake manifold to reduce the radiate sound. In addition, the rigidity of at least a portion of each of the junctions included in the intake manifold can be further increased by the connection of the rib to the junctions between the plurality of bonded parts forming at least a portion of the surge tank.
According to an eighth aspect and feature of the present invention, in addition to the first feature, a lattice-shaped rib is projectingly provided on an outer surface of the main tank portion on the side of the engine body and connected to junctions between the plurality of bonded parts forming at least a portion of the surge tank. With such arrangement, the lattice-shaped rib is provided on the outer surface of the main tank portion on the side of the engine body forming a portion of the surge tank by effectively utilizing a space between the engine body and the surge tank. Therefore, the rigidity of the surge tank can be increased remarkably, while avoiding an increase in size of the intake manifold, thereby increasing the entire rigidity of the intake manifold to reduce the radiated sound. In addition, the rigidity of at least a portion of each of the junctions included in the intake manifold can be further increased by the connection of the rib to the junctions between the plurality of bonded parts forming at least a portion of the surge tank.
According to a ninth aspect and feature of the present invention, in addition to the first feature, a flange is commonly connected to the plurality of intake pipes and fastened to the engine body, and includes a base plate formed into a flat shape and connected commonly to the intake pipes, a plurality of connecting tubular portions which have endless seal-mounting grooves in end faces thereof on the side of the engine body, and individually lead to the intake pipes to be connected to the base plate, a plurality of boss portions which are formed into a tubular shape with bolt-insertion bores provided therein for fastening the flange to the engine body, and are connected to the base plate so as to be respectively disposed at least at upper and lower locations between the connecting tubular portions, and a plurality of radiate ribs which extend radiately from the boss portions and are connected to the base plate so as to be connected to the connecting tubular portions adjacent the boss portions, wherein a plurality of seal members are mounted in the seal-mounting grooves, respectively and interposed between the flange and the engine body.
With the such arrangement of the ninth feature, the fastening rigidity of the entire flange to the engine body can be increased by the radiate ribs extending radiately from the boss portions and connecting the boos portions and the connecting tubular portions, while avoiding an increase in thickness of the entire flange to prevent an increase in weight of the flange. Moreover, a fastening force is applied to a plurality of circumferential points of each of the connecting tubular portions from the boss portions through the radiate ribs, leading to an enhancement in sealing performance provided by the seal members mounted in the seal-mounting grooves provided in the end faces of the connecting tubular grooves on the side of the engine body.
According to a tenth aspect and feature of the present invention, in addition to the first feature, a flange is commonly connected to the plurality of intake pipes and fastened to the engine body, and includes a base plate formed into a flat shape and connected commonly to the intake pipes, a plurality of connecting tubular portions, which have endless seal-mounting grooves and grooves in end faces thereof on the side of the engine body, the latter grooves being connected at inner ends thereof to the seal-mounted grooves and opening at outer ends thereof into a side of the flange, the connecting tubular portions individually leading to the intake pipes and being connected to the base plate, a plurality of boss portions which are formed into a tubular shape with bolt-insertion bores provided therein for fastening the flange to the engine body, and are connected to an outer periphery of the base plate so as to be respectively disposed at least at upper and lower locations between the connecting tubular portions, and an outer peripheral rib which connects the connecting tubular portions and the boss portions to each other, and are connected to opposite sides of the grooves in the connecting tubular portions and to the outer periphery of the base plate, wherein a plurality of seal members integrally provided with protrusion to be fitted into the latter grooves are mounted in the seal-mounting grooves, respectively and interposed between the flange and the engine body.
With the arrangement of the tenth feature, the fastening rigidity of the flange to the engine body can be increased by the outer peripheral rib disposed around the outer periphery of the flange to connect the boss portions and the connecting tubular portions to each other, while avoiding an increase in thickness of the entire flange to prevent an increase in weight of the flange. Moreover, the seal members mounted in the seal-mounting grooves provided in the end faces of the connecting tubular portions on the side of the engine body are integrally provided with the protrusions which are to be fitted into the grooves provided in the end faces of the connecting tubular portions with their inner ends connected to the seal-mounting grooves and with their outer ends opening into the side of the flange. Therefore, in a state in which the flange has been fastened to the engine body, the presence or absence of the protrusions, i.e., the presence or absence of the seal member can be visually checked from outside the flange. In addition, since the outer peripheral rib is connected to the connecting tubular portions on the opposite sides of the grooves, it is possible to prevent a reduction in rigidity of the connecting tubular portions due to the provision of the grooves, to inhibit a reduction in sealing performance provided by the seal members, and to reduce the length of each of the grooves and the size of the protrusions of the seal members, while avoiding an increase in size of the flange.
According to an eleventh aspect and feature of the present invention, in addition to the arrangement of the first feature, the bonded part forming a portion of the surge tank is formed with a bent portion bent toward the inside of the surge tank, the bent portion being provided at an outer surface thereof with a rib connected to a junction between the bonded part having the bent portion and the other bonded part. With such arrangement, the rigidity of a portion of the bonded part at a location facing the surge tank can be increased by the bent portion bent toward the inside of the surge tank and by the rib formed on the outer surface of the bent portion. In addition, since the rib is connected to the junction, the pressure-resistant strength of the junction to a variation in pressure can be increased with a simple structure and thus, the durability of the junction can be enhanced. Moreover, since the bent portion is disposed to face the inside of the surge tank, an influence exerted on a flow of intake air flowing within the intake manifold by the bent portion is small.
According to a twelfth aspect and feature of the present invention, in addition to the eleventh feature, the bonded part having the bent portion is formed with a bonding collar protruding from the bent portion to become bonded to the other bonded part. With such arrangement, the bent portion is formed on one of a pair of the bonded parts in proximity to the junction between such pair of bonded parts and hence, it is possible to further enhance the durability of the junction bonding both of the bonded parts.
According to a thirteenth aspect and feature of the present invention, in addition to the first feature, at least one of the bonded parts is formed with a pressure-variation absorbing portion for absorbing a variation in pressure within each of the surge tank and the intake pipes by the flexing thereof. With such arrangement, when the pressure within the intake manifold is varied, the pressure-variation absorbing portion is flexed to absorb such variation in pressure. Therefore, it is possible to reduce a load applied to the junctions between the bonded parts, leading to an increase in pressure-resistant strength of the junctions to contribute to an enhancement in durability of the junctions.
According to a fourteenth aspect and feature of the present invention, in addition to the thirteenth feature, the pressure-variation absorbing portion of a shape bent toward the inside of the surge tank is formed on the bonded part forming a portion of the surge tank. With such arrangement, the durability of the junction can be enhanced with a simple structure. Further, the pressure-variation absorbing portion is disposed to face the inside of the surge tank and hence, an influence exerted on a flow of intake air flowing within the intake manifold by the pressure-variation absorbing portion is small.
The above and other objects, features and advantages of the invention will become apparent from the following description of the preferred embodiments taken in conjunction with the accompanying drawings.